1. Field of the Invention
The present invention relates to a color image editing apparatus capable of changing a certain color designated in an image to another color.
2. Description of the Related Art
In a conventional color image editing apparatus for use in a color copying machine, a color original is placed on an editor pad, so that a certain color present on the color original is designated to store the color to be changed. Subsequently, after scanning the original color image, partial color converting process is carried out in such a manner that the portion in the color original, which is colored by the stored color to be converted, is subjected to color conversion to be colored with another color.
In this case, the reading operation by the scanner is achieved not in an equivalent color spatial coordinate system such as density (V), hue (H) and saturation (C) but in a color display coordinate system with R, G, B or Y, M, C. Accordingly, it is difficult to uniformly detect the colors having high density and low density. There may ocuur problems that if the detection range is narrowed in order to improve detection accuracy, the color detection is performed imperfectly, and also if the detection range is broadened, the color detection is carried out eroneously.
In view of these problems, there has been proposed such a color image editing apparatus in Published Unexamined Japanese Patent Application No. 143561/1989 that while the color judgement is executed, a natural color-converted image can be obtained by merely substituting the color of the designated hue with the color of other hue with the density, hue, and chroma.
When image data is color-converted with regard to the density (V), hue (H) and saturation (C), the color conversion can be done by only changing the H (density) data. However, the H data substitution cannot convert the converted color into the achromatic (neutral) color. Furthermore, since a difference by hue in colors adjacent a gray color becomes very small, color discrimination becomes difficult if a simple judgement is made. Moreover, since the chroma detecting sensitivities are varied in accordance with density of the color, there is such a problem that the colors having low density are recognized as gray eroneously.